Emma had three reasons for telling Sophie and one reason for not telling her. The reason for not telling her was the same one she'd had for a week: sharing a mystery before you understood it could redirect the search before you'd set your own direction. But the map was past that stage now. She had a direction — she just didn't know where it led — and Sophie's instincts were the kind that found things in the spaces between what you'd already found. She made leaps.

Also, Emma was going to the island on Saturday. It would be stranger, at this point, not to tell her.

She unfolded the map on the corner table at lunch on Tuesday and said: 'I need to tell you about something.'

Sophie looked at the map for approximately four seconds. Then she looked at Emma. Then she looked at the map again. Then she said, 'Where did you get this?' in a voice that was quieter than Sophie's usual voice, which was how Emma knew she understood immediately that this was the kind of thing you spoke quietly about.

Emma told her everything. The library book. Mrs. Okafor and the checkout card. E. Marsh, 1952. The local history section. The newspaper clipping: Eleanor Marsh, naturalist, presents findings to county board. The lake on Saturday. The island. The boot print. The metal ring. The man on the eastern shore. H.W. in the lower left corner, different ink, different hand.

Sophie listened without interrupting, which was not Sophie's default mode and was therefore significant.

When Emma finished, Sophie sat for a moment. Then: 'The dotted line continues to the eastern shore.'

'Yes.'

'Where the man was standing.'

'Yes.'

'H.W. Marsh. Elmwood Drive.'

'Fourteen Elmwood.'

Sophie looked at the map again. At the initials in the lower left corner. 'He added himself to her map.'

'That's how I read it.'

'That's not what you do to a stranger's map,' Sophie said. 'You don't write your initials in the corner of a stranger's map. You do that if the map means something to you personally. If you feel like you have a right to it.'

Emma had thought this but hadn't said it in quite that way. 'He's related to her,' she said.

'Or he was very close to her. Or both.' Sophie looked up. 'Have you talked to him?'

'He's the man who never talks to anyone.'

'On Elm Street.'

'He's been there my whole life and I've never heard anyone have a real conversation with him.'

Sophie thought about this. 'That's interesting. Because the people who never talk to anyone usually have the most to say.' She paused. 'Or the most to not say. Which is a different thing.'

'I know.'

'When are you going to the island?'

'Saturday. Jake got the canoe from Mr. Harmon.'

Sophie looked at her with an expression that combined delight and the kind of calm certainty that meant a decision had already been made. 'I'm coming.'

Emma had expected this. 'There are four life vests.'

'Perfect. Because Marco is also coming.'

'I haven't asked Marco.'

'I will.' Sophie refolded the map along its lines — she had noticed the lines and was being careful about them — and pushed it back across the table to Emma. 'He'll want to come. He's been curious about that lake his whole life too.'

'He has?'

'We all have. We live four blocks from it and none of us have ever gone. That's the kind of thing you notice eventually.'

Emma put the map back in her jacket pocket. Sophie was right — the lake had been there, available, her whole life, and she had never gone until last Saturday. The curious thing was not that she'd gone. The curious thing was why none of them had gone before.

'Don't tell anyone else,' Emma said.

'Obviously,' Sophie said, in the tone of someone who found the instruction unnecessary but understood why it had been given.